The present invention relates to a constriction device which can be at least partially implanted in the human or animal body. The invention will be described more particularly with respect to a gastric constriction device of the xe2x80x9cgastroplasty ringxe2x80x9d type which can be used for treating morbid obesity.
However, the invention is not limited to such an application or use. The invention is also usefully employed in various medical interventions on humans and animals in which it is necessary to obtain a temporary or permanent constriction, or if appropriate an occlusion, of an organ or conduit or canal.
In the field of gastric constriction, there are several reasons for wanting to control an individual""s gastric intake of food, particularly, but not exclusively, in the case of an individual suffering from morbid obesity, or, for example, in cases of diabetes, hypercholesterolemia, or high blood pressure. The expression xe2x80x9cmorbid obesityxe2x80x9d is understood to mean that an individual is at least 45 kg overweight, or at least equal to his ideal weight, as can be defined on the basis of his height and by means of a table for calculating body mass index.
Several surgical techniques are known for trying to treat this obesity, for example by connecting the stomach directly to the small intestine. Another technique consists in placing sutures or staples vertically or horizontally in the stomach wall in order to define a pouch of reduced size compared with that of the stomach, which limits the quantity and speed of transit of the food which can be ingested. However, although these earlier solutions are relatively effective, they are also fairly traumatizing and are rarely if at all reversible, and their feasibility by peritoneoscopy is somewhat uncertain.
Another proposed solution has been to place an inflatable balloon inside the stomach, which gives the patient the constant feeling of being sated. Such a device has been described in patent U.S. Pat. No. 4,416,267. However, fitting balloons of this type has led to a number of not inconsiderable complications, such as intestinal blockages and stomach ulcers, and it takes no account of the risk to the patient associated with prolonged contact of a foreign object with the gastric mucosa.
Finally, a much less traumatizing approach is one in which a gastric constriction device is used comprising firstly a gastric constriction member forming a ring in its operational configuration, for example comprising a flexible band whose two ends are adjacent to one another in the operational configuration, equipped with an inflatable balloon, surrounding the outer wall of the stomach, secondly a means for actuating the gastric constriction member, for example a valve or fluid injector for injecting or introducing said fluid into the balloon, and thirdly a remote control for controlling the actuating means, for example a fluid introduction chamber situated just below the skin at a site relatively easy for the patient to access. The control means and the actuating means are connected via a flexible conduit, for example a catheter, making it possible to transmit the fluid from the chamber to the actuating means. Such a device has the advantage that it can be introduced into the body by peritoneoscopy or laparoscopy, which significantly reduces the trauma and postoperative complications of the surgical intervention compared with xe2x80x9copenxe2x80x9d surgery, that is to say classical abdominal surgery. However, such a device has the disadvantage that the chamber is quite bulky in the long term. A device corresponding to the above description has been developed by and is known for example from the works of Doctor Kuzmak, and reference may usefully be made to the patents or patent applications WO-A-92/02182, U.S. Pat. No. 4,592,339, EP-A-0611561, WO-A-86/04498, WO-A-94/27504 and U.S. Pat. No. 5,226,429.
However, none of the solutions thus far proposed permits precise control of the degree of gastric constriction. In the case of the devices from Doctor Kuzmak, the volumes of injectable fluid are limited and they represent a solution which is difficult to control with precision. It is possible for a certain volume of fluid to be injected into or withdrawn from the balloon, but the intrinsic elasticity of the latter varies depending on the biological conditions of its implantation, and over the course of time, which makes its expansion difficult to control, and insufficiently adapted to the desired or desirable treatment. Moreover, the manual actuation, for example the patient pressing the subcutaneous push button, or even the accidental actuation of the latter, can have undesirable consequences, for example the need for a repeat intervention, or disinfection of the equipment, etc.
It is known to produce a constriction device which can be at least partially implanted in the human or animal body, comprising a constriction member forming a ring in its operational configuration, said constriction member including a flexible band whose two ends are adjacent to one another in the operational configuration, and a means for actuating the constriction member.
A gastric constriction device with flexible band, implanted and closed on itself about the stomach, is also known from document EP-0876808.
In its operational configuration, the flexible band includes on its inner face a flexible wall which delimits a cavity filled with a variable volume of liquid originating from an equalizing reservoir which is also implanted in the patient""s body.
A remote-controlled pump can transmit the liquid from the equalizing reservoir to the gastric band, and vice versa, by way of an electrical control unit. The latter is mounted with the pump in a control housing implanted under the patient""s skin.
Besides the disadvantages already mentioned concerning this type of device, there are risks associated with possible leaks of liquid following incorrect manipulation or resulting from manufacturing defects.
Moreover, the inflation of the gastric band promotes the appearance of folds on its inner wall in contact with the stomach. A uniform constriction is thus no longer applied to the periphery of the stomach, and there is an increased risk of pinching the stomach wall in a fold.
The pump is powered by an electrical power source implanted in the body, which can be dangerous depending on the materials constituting such a source, for example an electric battery.
In addition, document U.S. Pat. No. 3,840,018 discloses a device which can be at least partially implanted in the human or animal body, comprising a constriction member forming a ring and a means for actuating this constriction member. The ring which this constriction member forms includes a flexible band, of which at least one of the ends includes a tractile element; the tractile end of the flexible band is moved inside a hollow element of the device via a pulling member which the actuating means comprises. This pulling member is made up of an endless screw with which it is possible to generate a radial deformation of the constriction member.
The document DE 19718903 describes, like the above patent U.S. Pat. No. 3,840,018, all the characteristics set out in the preamble of claim 1.
The present invention proposes a constriction device with which it is possible to overcome the disadvantages of the devices of the prior art and to regulate, in a very precise and reproducible manner, the constriction applied to any organ or conduit of the human or animal body, while avoiding or limiting any surgical intervention required for this control. It is a particular object of the invention to prevent the tractile end of the flexible band from damaging the anatomical environment, in which the device is implanted, when it is moved by the pulling member.
According to the present invention, on the one hand at least one end of the flexible band includes a tractile element for moving said end relative to the other end, generating a radial deformation of the constriction member, and, on the other hand, the actuating means comprises a member for pulling the tractile element. According to an advantageous embodiment of the invention, the tractile element is lamelliform. According to an advantageous embodiment, the flexible band is fixed via one of its ends to the body of the actuating means and includes the tractile element at its other end. Said tractile element comprises pulling means, for example notches, which are able to cooperate with the pulling member of the actuating means.
The device of the present invention is also distinguished by the fact that, in the standby configuration of the constriction member, between these two ends, the flexible band is made up of a first element including a first fixing member, for example male, and a second element including a complementary second fixing member, for example female, the first element being connected to the second element by definitive coupling of the complementary fixing members, in order to obtain the operational configuration of the constriction member.
According to an advantageous embodiment of the constriction device, the fixed end of the flexible band is traversed by a slit, which is longitudinal and open, and is able to receive a tongue, of reduced width, of the tractile element. The constriction member advantageously includes a sheath made of compressible or pliable biocompatible material, enclosing the flexible band. This sheath ensures that the constriction member is biocompatible with the outer wall of the stomach because the gastric constriction device must remain in place for a relatively long period in order to obtain a satisfactory clinical result, and it is therefore preferable to reduce as far as possible the risks of lesions due to contact of a foreign body with the tissues of the stomach wall.
The actuating means advantageously comprises a bi-directional motor coupled to the pulling member.
The pulling member according to the invention meshes with the pulling means in order to move the tractile element in a longitudinal and circumferential direction of the constriction member.
According to an advantageous embodiment, the pulling member is a tangent screw, while the pulling means are regularly spaced notches transverse to the longitudinal direction, and the threading of the tangent screw has the same pitch as that separating the pulling notches.
The constriction device advantageously includes a protective shell which has a part of rigid material forming a motor housing, and a part of compressible or pliable biocompatible flexible material forming the sheath of the flexible band.
The casing and the sheath advantageously form one and the same piece.
The sheath advantageously has material recesses on each side of the flexible band, and/or preformed folds, allowing said sheath to fold in an ordered and regular manner upon radial deformation of the constriction member.
According to an interesting embodiment, the device comprises or is associated with a remote control means. The latter can comprise an extracorporeal emitter and an intracorporeal receiver, the latter having a means for processing a signal emitted by the emitter and for transmitting a control signal to the actuating means. The processing means can comprise a single electric circuit designed to carry both control information and power to the actuating means.
The processing means can advantageously comprise an electric circuit consisting of a resonance induction coil, a rectifier, a pulse generator, at least one shift register circuit, and a circuit for controlling the direction of running of the actuating means.
By way of example, according to the invention the receiver of the control means is arranged remote from the constriction member and is connected electrically to the actuating means.
According to another advantageous illustrative embodiment of the device according to the invention, the extracorporeal emitter comprises an electric circuit made up of an electrical power supply, an oscillator, an amplifier circuit and a primary induction coil.
The emitter can additionally comprise at least one member for selecting the frequency of the oscillator.
The constriction device according to the invention is also distinguished by the fact that the actuating means is designed to retain, in a stable manner, the mutual relative position of the two ends of the flexible band in the absence of power supply to said actuating means.